The present invention relates to a method of transferring an electrical load from one AC voltage source to another with no interruption of voltage during the switch.
There are several circumstances in which a load must be transferred from one AC voltage source to another. One example of such a circumstance is transferring a load from an electrical power grid to a generator in case of an anticipated power outage. Another example of such a circumstance is phase balancing, in which a load is transferred from one phase to another.
Prior art methods of transferring a load from one AC voltage source to another all entail an interruption of voltage for at least a short time interval. The duration of this time interval depends on the speed of the switching circuit used. In high current applications, the switching circuits are mechanical devices that are capable of withstanding high currents and very high short-circuit currents.
Many systems stop working, or else reset themselves, when their voltage supplies are interrupted or are significantly disturbed.
There is thus a widely recognized need for, and it would be highly advantageous to have, a method of transferring a load from one AC voltage source to another AC voltage source with no interruption of the voltage, with minimal distortion of the voltage and of the current, and with no interruption of the functioning of the load.